Difference in Load Data?

[kayak-man]

I have another thread running on my attempts to load 9mm, but my gut feeling is this topic deserves its own thread...

SHORT VERSION: Should I be concerned that the load data in my reloading manuel is different from the load data on the powder manufactureres website?

LONG VERSION:
In my other thread where I was trying to figure out how much crimp to use, I posted the load data in my Lee reloading manuel which I was planning on using, which someone pointed out was a fairly hot load.

I'm reloading 9x19 using a 115grain jacketed bullet, with Accurate #7 powder. The Lee manual lists the STARTING load as 7.7grains. The load data on the AccuratePowders website? Well, they list the Do Not Exceed load at 7.8 Grains

Could someone tell me whats going on here? As far as I can tell, the smart move is going to be to use a starting load somewhere around 6.7 Grains (what the AccuratePowders load data lists), bring a squib rod just incase, and slowly work my way up.

But, that still doesn't explain why the Lee manual lists the starting load as only one tenth of a grain less than the powder manufacturers never exceed load....

Chris "the Kayak-Man" Johnson

 

[T Bran]

I allways use the powder manufacturers data. When your manual was written im sure this was considered a safe load but all batches of powder are not the same even though the number is. For this reason if ever you aquire very old powder you need to find a manual of the same age. Also as pressure testing equipment gets better some loads have been found to be hotter than previously thought. Since load books are out for many years between publishings they have no way to update them untill the next publishing. The powder company can and often does change loadings on the website due to newer data that the books wont reflect untill the next publishing.
Ive even read that some reloaders work up a load with a powder and store some extra away that is of the same lot number since the next batch may be slightly different.
T

 

[gamestalker]

I wouldn't be concerned about a squib with that powder, it's one of the slower burner's for the 9x19 and still gets the job done at the lower end of data.

 

[ranger335v]

"Should I be concerned that the load data in my reloading manuel is different from the load data on the powder manufactureres website?"

Not a bit. No data source is more than educated suggestion anyway, the end result is ALWAYS up to us because every gun is unique. Those who say some sources are better than others or that any of them are 'lawyered up' are wrong; each source tell us exactly what they got in their rigs and that's all they can tell us. Our rigs are different from theirs so our results will also be somewhat different, sometimes by quite a bit. All suggested start loads will safe in anything in decent condition, all max loads may be an overcharge in some rigs.

Bottom line, we must start low and slowly work up, certainly with any new gun we haven't proven. As we move up we MUST keep looking for signs of excessive pressure and stop if we find them; there is no value in 'working up slowly' if we're going to ignore what's happening until we reach book max anyway!

 

[MEHavey]

9mm is kinda squirrelly, and best demonstrates why people have multiple loading manuals:

For AA #7/115gr TMJ/9x19 and/or 9mm Luger

Speer#14  MIN-8.6gr -- MAX-9.6C  [Really(!)]
Sierra#5  MIN-7.0gr -- MAX-8.6
Lyman#48  MIN-6.7gr -- MAX-8.5
Hornady#6 MIN-7.0gr -- MAX-8.6

BTW: QL predicts that 8.6gr Load with a Speer 155/TMJ at 1.135" is a full case and a 36,000psi load (at the stops)
But QL isn't at its best w/ straightwall cases

Were it me, I'd go with the Sierra/Lyman/Hornady regimes--checking for specific bullet & OAL
But when all the dust settles, 7.7gr seems an interesting point to check slide function.

 

[James2]

Bottom line, we must start low and slowly work up, certainly with any new gun we haven't proven. As we move up we MUST keep looking for signs of excessive pressure and stop if we find them; there is no value in 'working up slowly' if we're going to ignore what's happening until we reach book max anyway!

I certainly agree with this.

It is our responsibility to build safe ammo. The manuals give us a place to start.

 

[Clark]

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

Here are some signs of excessive pressure I found when I started handloading 9mm with 115 gr JHP and AA#5.

Don't work up until you blow a hole, like I did.

You want to look for case bulges that are precursors to case blow outs, and look for pierced primers. Then reduce the load until that pressure sign goes away, and then reduce by enough safety margin so you know if you are making large quantities of ammo that it is all safe.

Here is a picture of one of my guppy belly case bulges. The thin case wall over the unsupported part of the chamber over the feed ramp, has bulged.

You don't want that.

Before you get to real pressure signs in a 9mm work up, there should be intolerable recoil.

You can tune the reloads to the gun and have the brass land 5 feet from the shooter, or you can tune the recoil springs to the load and have the brass land 5 feet from the shooter.

With 48 pound triple recoil springs in my Glock 19, hot load still get sent way to far and the slide slams into the frame.

Most commercial 9mm pistols will have case support .19" from the breech face over the feed ramp. 9mm brass has a .16" web. This means that real pressure signs will probably not appear before intolerable recoil, recoil unmanageable with spring changes appears.

Quickload thinks that 7.8 gr AA#7 115 gr JHP is ~ 17kpsi, so I doubt you will see either great pressure or great recoil.

 

[steve4102]

The load data on the AccuratePowders website? Well, they list the Do Not Exceed load at 7.8 Grains

Not sure what data you are referring to, but Accurate Powder's web site lists the following.
9MM Luger
115gr Nosler FMJ
Accurate #7--Start-7.9gr---Max 8.8gr
COAL 1.095in.
Link to data.
http://www.accuratepowder.com/wp-content/uploads/2010/12/accurate_load_data_3.4.pdf